NAME

auditd.conf - audit daemon configuration file

DESCRIPTION

The file /etc/audit/auditd.conf contains configuration information
specific to the audit daemon. It should contain one configuration
keyword per line, an equal sign, and then followed by appropriate
configuration information. The keywords recognized are: log_file,
log_format, log_group, priority_boost, flush, freq, num_logs , disp_qos
, dispatcher, name_format , name, max_log_file, max_log_file_action,
space_left, action_mail_acct, space_left_action, admin_space_left,
admin_space_left_action, disk_full_action, and disk_error_action.
These keywords are described below.
log_file
This keyword specifies the full path name to the log file where
audit records will be stored. It must be a regular file.
log_format
The log format describes how the information should be stored on
disk. There are 2 options: raw and nolog. If set to RAW, the
audit records will be stored in a format exactly as the kernel
sends it. If this option is set to NOLOG then all audit
information is discarded instead of writing to disk. This mode
does not affect data sent to the audit event dispatcher.
log_group
This keyword specifies the group that is applied to the log
file’s permissions. The default is root. The group name can be
either numeric or spelled out.
priority_boost
This is a non-negative number that tells the audit damon how
much of a priority boost it should take. The default is 3. No
change is 0.
flush Valid values are none, incremental, data, and sync. If set to
none, no special effort is made to flush the audit records to
disk. If set to incremental, Then the freq parameter is used to
determine how often an explicit flush to disk is issued. The
data parameter tells the audit damon to keep the data portion of
the disk file sync’d at all times. The sync option tells the
audit daemon to keep both the data and meta-data fully sync’d
with every write to disk.
freq This is a non-negative number that tells the audit damon how
many records to write before issuing an explicit flush to disk
command. this value is only valid when the flush keyword is set
to incremental.
num_logs
This keyword specifies the number of log files to keep if rotate
is given as the max_log_file_action. If the number is < 2, logs
are not rotated. This number must be 99 or less. The default is
0 - which means no rotation. As you increase the number of log
files being rotated, you may need to adjust the kernel backlog
setting upwards since it takes more time to rotate the files.
This is typically done in /etc/audit/audit.rules.
disp_qos
This option controls whether you want blocking/lossless or non-
blocking/lossy communication between the audit daemon and the
dispatcher. There is a 128k buffer between the audit daemon and
dispatcher. This is good enogh for most uses. If lossy is
chosen, incoming events going to the dispatcher are discarded
when this queue is full. (Events are still written to disk if
log_format is not nolog.) Otherwise the auditd daemon will wait
for the queue to have an empty spot before logging to disk. The
risk is that while the daemon is waiting for network IO, an
event is not being recorded to disk. Valid values are: lossy and
lossless. Lossy is the default value.
dispatcher
The dispatcher is a program that is started by the audit daemon
when it starts up. It will pass a copy of all audit events to
that application’s stdin. Make sure you trust the application
that you add to this line since it runs with root privileges.
name_format
This option controls how computer node names are inserted into
the audit event stream. It has the following choices: none,
hostname, fqd, numeric, and user. None means that no computer
name is inserted into the audit event. hostname is the name
returned by the gethostname syscall. The fqd means that it takes
the hostname and resolves it with dns for a fully qualified
domain name of that machine. Numeric is similar to fqd except
it resolves the IP address of the machine. User is an admin
defined string from the name option. The default value is none.
name This is the admin defined string that identifies the machine if
user is given as the name_format option.
max_log_file
This keyword specifies the maximum file size in megabytes. When
this limit is reached, it will trigger a configurable action.
The value given must be numeric.
max_log_file_action
This parameter tells the system what action to take when the
system has detected that the max file size limit has been
reached. Valid values are ignore, syslog, suspend, rotate and
keep_logs. If set to ignore, the audit daemon does nothing.
syslog means that it will issue a warning to syslog. suspend
will cause the audit daemon to stop writing records to the disk.
The daemon will still be alive. The rotate option will cause the
audit daemon to rotate the logs. It should be noted that logs
with higher numbers are older than logs with lower numbers. This
is the same convention used by the logrotate utility. The
keep_logs option is similar to rotate except it does not use the
num_logs setting. This prevents audit logs from being
overwritten.
action_mail_acct
This option should contain a valid email address or alias. The
default address is root. If the email address is not local to
the machine, you must make sure you have email properly
configured on your machine and network. Also, this option
requires that /usr/lib/sendmail exists on the machine.
space_left
This is a numeric value in megabytes that tells the audit daemon
when to perform a configurable action because the system is
starting to run low on disk space.
space_left_action
This parameter tells the system what action to take when the
system has detected that it is starting to get low on disk
space. Valid values are ignore, syslog, email, exec, suspend,
single, and halt. If set to ignore, the audit daemon does
nothing. syslog means that it will issue a warning to syslog.
Email means that it will send a warning to the email account
specified in action_mail_acct as well as sending the message to
syslog. exec /path-to-script will execute the script. You
cannot pass parameters to the script. suspend will cause the
audit daemon to stop writing records to the disk. The daemon
will still be alive. The single option will cause the audit
daemon to put the computer system in single user mode. halt
option will cause the audit daemon to shutdown the computer
system.
admin_space_left
This is a numeric value in megabytes that tells the audit daemon
when to perform a configurable action because the system isrunninglow on disk space. This should be considered the last
chance to do something before running out of disk space. The
numeric value for this parameter should be lower than the number
for space_left.
admin_space_left_action
This parameter tells the system what action to take when the
system has detected that it islowondiskspace. Valid values
are ignore, syslog, email, exec, suspend, single, and halt. If
set to ignore, the audit daemon does nothing. Syslog means that
it will issue a warning to syslog. Email means that it will
send a warning to the email account specified in
action_mail_acct as well as sending the message to syslog. exec
/path-to-script will execute the script. You cannot pass
parameters to the script. Suspend will cause the audit daemon
to stop writing records to the disk. The daemon will still be
alive. The single option will cause the audit daemon to put the
computer system in single user mode. haltdisk_full_action
This parameter tells the system what action to take when the
system has detected that the partition to which log files are
written has become full. Valid values are ignore, syslog, exec,
suspend, single, and halt. If set to ignore, the audit daemon
does nothing. Syslog means that it will issue a warning to
syslog. exec /path-to-script will execute the script. You
cannot pass parameters to the script. Suspend will cause the
audit daemon to stop writing records to the disk. The daemon
will still be alive. The single option will cause the audit
daemon to put the computer system in single user mode. halt
option will cause the audit daemon to shutdown the computer
system.
disk_error_action
This parameter tells the system what action to take whenever
there is an error detected when writing audit events to disk or
rotating logs. Valid values are ignore, syslog, exec, suspend,
single, and halt. If set to ignore, the audit daemon does
nothing. Syslog means that it will issue a warning to syslog.
exec /path-to-script will execute the script. You cannot pass
parameters to the script. Suspend will cause the audit daemon
to stop writing records to the disk. The daemon will still be
alive. The single option will cause the audit daemon to put the
computer system in single user mode. halt option will cause the
audit daemon to shutdown the computer system.

NOTES

In a CAPP environment, the audit trail is considered so important that
access to system resources must be denied if an audit trail cannot be
created. In this environment, it would be suggested that /var/log/audit
be on its own partition. This is to ensure that space detection is
accurate and that no other process comes along and consumes part of it.
The flush parameter should be set to sync or data.
Max_log_file and num_logs need to be adjusted so that you get complete
use of your partition. It should be noted that the more files that have
to be rotated, the longer it takes to get back to receiving audit
events. Max_log_file_action should be set to keep_logs.
Space_left should be set to a number that gives the admin enough time
to react to any alert message and perform some maintenance to free up
disk space. This would typically involve running the aureport-t report
and moving the oldest logs to an archive area. The value of space_left
is site dependant since the rate at which events are generated varies
with each deployment. The space_left_action is recommended to be set to
email. If you need something like an snmp trap, you can use the exec
option to send one.
Admin_space_left should be set to the amount of disk space on the audit
partition needed for admin actions to be recorded.
Admin_space_left_action would be set to single so that use of the
machine is restricted to just the console.
The disk_full_action is triggered when no more room exists on the
partition. All access should be terminated since no more audit
capability exists. This can be set to either single or halt.
The disk_error_action should be set to syslog, single, or halt
depending on your local policies regarding handling of hardware
malfunctions.